The present invention is directed to a low insertion force or zero insertion force connector for printed circuit boards and integrated circuit devices.
The printed circuit boards typically have one or more rows of conductive pads located along an edge of the board. The conductive pads are typically spaced between 0.010 to about 0.025 inches apart. The conductive pads are electrically connected to the integrated circuit packages by routing layers or traces on the printed circuit board. The edge of the board and the surface pads can be plugged into a corresponding connector within a larger assembly. The integrated circuits are coupled to the larger assembly through the routing layers, the conductive pads and the connector. The connectors are commonly referred to as card edge connectors.
The printed circuit board assemblies are typically tested in a test fixture after the integrated circuit packages have been soldered to the board. The tester may have a card edge connector that is mounted on a test board. The circuit board assembly is tested by manually pushing the board into the card edge connector.
Card edge connectors typically have a plurality of spring like contacts, which are pressed into the conductive pads. To plug in a board, the operator must exert enough force to overcome the spring force of the contacts. A production facility may produce thousands or millions of printed circuit boards, which must be plugged into the test connector. The repetitiveness of inserting so many circuit boards into the test connector may cause the card edge connector contacts to wear out. Eventually, the card edge connector will need to be replaced. The contacts on the connector can also scar the conductive pads on the printed circuit board.
Many of the same difficulties associated with testing printed circuit boards also arise in the testing of integrated circuit devices. In addition to the problems described above, the leads on integrated circuit devices can be easily damaged during insertion into and removal from a test fixture.
WO 98/50985 discloses a multi-mode compliant connector for various circuit devices. U.S. Pat. No. 4,593,961 discloses an electrical compression connector.
Low insertion force or zero insertion force connectors are preferred in those instances where it is desired to minimize wear on the contacts and to minimize damage to the printed circuit board conductive pads or leads on an integrated circuit device.
The present invention relates to a connector for electrically connecting integrated circuit devices or printed circuit boards to a second circuit member. The second circuit member may be a motherboard, back plane, or the like. The present invention interfaces with the same conductive pads as a traditional edge card connector. The conductive pads may be located on one or both side of the printed circuit board, and can be in a single row or multiple levels of rows.
In one embodiment, the connector apparatus comprises a connector housing having one or more apertures. One or more contact members are positioned within each of the apertures. Each contact member has a first interface portion adjacent to a receiving opening in the housing and a second interface portion. The contact members are moveable between an engaged and a disengaged position within the receiving opening. A first compliant material retains the contact members to the connector housing. A second compliant material is positioned to bias the contact members toward the engaged position. An actuator is releasably engages with the housing. The contact members are biased toward the engaged position when the actuator is engaged with the housing.
In a zero insertion force embodiment, the contact members in the disengaged position provide no resistance to insertion of a first circuit member into the receiving opening. In a low insertion force embodiment, the contact members provide minimal resistance to insertion of the first circuit member into the receiving opening.
The contact members typically abut the connector housing in the disengaged position. The contact members pivot against the connector housing when moving between the disengaged position and the engaged position. The actuator typically includes an opening permitting a first circuit member to extend into the receiving opening.
The second compliant member can be attached to the actuator. In one embodiment, the first compliant material is positioned between the contact members and the connector housing and a second compliant material is positioned between the contact members and the actuator. The actuator is typically engaged with the housing in response to the first circuit member being inserted into the receiving opening.
The first compliant material has a Durometer greater than, less than, or equal to, a Durometer of the second compliant material. The contact members can include one or more recesses for receiving a portion of the first compliant material.
The contact members can be flexible or rigid. In an embodiment where the contact members are flexible, in the engaged position the first and second compliant members primarily provide the first mode of compliance and elastic deformation of the flexible contact members primarily provides the second mode of compliance.
The first circuit interface portion can optionally have a shape complementary to a shape of an electrical interface on a first circuit member. At least one support member can optionally support the contact member. The support member comprises a pivot point around which the contact members rotate. In one embodiment, the support member comprises a flexible filament capable of permitting translational and rotational movement of the contact members within the connector housing.
An adapter can optionally be interposed between the connector apparatus and a second circuit member. A base frame can optionally be attachable to the second circuit member. The connector housing, contact members and first compliant material comprise a removable contact set that can be easily replaced.
The present invention is also directed to a method of electrically connecting a first circuit member having a plurality of conductive pads to a second circuit member. One or more contact members are positioned within one or more apertures on a connector housing. Each contact member has a first interface portion adjacent to a receiving opening and a second interface portion. The contact members are moveable between an engaged and a disengaged position. A first compliant material is applied to retain the contact members to the connector housing. A connector housing is located on the second circuit member. An actuator is engaged with the housing to bias the contact members toward the engaged position. The step of inserting the first circuit member into the receiving opening can occur before or after the actuator is engaged with the housing. A second compliant member can be located between the actuator and the contact members.
The present connectors can be used in a test or burn-in environment for testing or exercising stand-along integrated circuit devices or printed circuit boards, whether bare boards or assembled units. The present connector is easy to use, has a long mechanical life and high electrical performance with minimal marking of the conductive pads or contact leads. The present connector may also be used in final assemblies.